A casino, or gambling house, is a place where games of chance are played and money won. While casinos have a wide variety of other attractions and amenities to attract gamblers, such as restaurants, theaters and shopping centers, they would not exist without the games themselves. Slot machines, blackjack, roulette and other games of chance make up the bulk of the billions of dollars in profits raked in by U.S. casinos each year.
A casino may be a standalone building, an entire island or even a cruise ship. Generally, casino buildings are designed with an architectural style that reflects the local culture. For example, the Venetian in Macau has been designed to bring the glamour of Venice to China and includes a Grand Canal Shoppes with gondoliers serenading guests on the water.
Gambling is illegal in some states and a casino must have high security to keep its patrons and staff safe. This is why Las Vegas and Atlantic City have incredibly high security and are heavily regulated by the government. Something about gambling (perhaps the fact that large amounts of money are involved) encourages people to cheat, steal and otherwise manipulate their way into a jackpot. Casinos spend a lot of time, effort and money on security.
In the past, many casinos were controlled by organized crime or mob families. However, real estate investors and hotel chains with deeper pockets began to buy out the gangsters and run their own casinos. With the threat of losing their gaming license at the slightest hint of mob involvement, legitimate casino owners have no interest in ties with organized crime.